Anglular position detection utilizing a plurality of rotary configured magnetic sensors

ABSTRACT

A magnetic sensing method and system include a die comprising a central location thereof. A group of magnetoresistive bridge circuits are located and configured upon the die. A magnetic biasing component is then utilized to bias the plurality of magnetoresistive bridge circuits with a magnetic field rotating about an axis of the central location of the die in order to generate a plurality of bridge output signals thereof. Finally, the plurality of bridge output signals are processed in order to determine position data thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 10/993,964, entitled “Position Detection Apparatusand Method for Linear and Rotary Sensing Applications,” which was filedwith the U.S. Patent & Trademark Office on Nov. 18, 2004, the disclosureof which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

Embodiments generally relate to sensing devices. Embodiments are alsorelated to magnetic sensing configurations based upon Hall-effect and/ormagnetoresistive components. Embodiments are additionally related toangular and rotary position sensors.

BACKGROUND OF THE INVENTION

Various sensors are known in the magnetic-effect sensing arts. Examplesof common magnetic-effect sensors include Hall-effect andmagnetoresistive technologies. Such magnetic sensors can generallyrespond to a change in the magnetic field as influenced by the presenceor absence of a ferromagnetic target object of a designed shape passingby the sensory field of the magnetic-effect sensor. The sensor can thenprovide an electrical output, which can be further modified as necessaryby subsequent electronics to yield sensing and control information. Thesubsequent electronics may be located either onboard or outboard of thesensor package.

Hall-effect sensing devices represent one type of magnetic-effectsensors that are utilized widely in rotational and angular positiondetection. Hall-effect sensors incorporate Hall-effect elements thatrely on a reaction between a current flowing between a first set ofcontacts and an orthogonally-applied magnetic field to generate avoltage across a second set of contacts. In theory, with no magneticfield applied to the Hall-effect element, no voltage should be generatedacross the second set of contacts. In practice, a voltage is typicallygenerated across the second set of contacts even with no magnetic fieldapplied to the Hall-effect element.

Magnetoresistive (MR) technology is also utilized in a variety ofcommercial, consumer and industrial detection applications. One type ofMR technology is anisotropic magnetoresistive (AMR) technology. In someconventional MR systems an apparatus can be provided for determining theposition of a member movable along a path. In such a device, a magnetcan be attached to the movable member and an array of magnetic fieldtransducers are located adjacent the path. This type of sensingconfiguration is commonly referred to as “MR Array” technology. As themagnet approaches, passes and moves away from a transducer, thetransducer provides a varying output signal, which can be represented bya single characteristic curve that is representative of any of thetransducers.

To determine the position of the movable member, the transducers areelectronically scanned and data is selected from a group of transducershaving an output that indicates relative proximity to the magnet. Acurve-fitting algorithm can then be utilized to determine a best fit ofthe data to the characteristic curve. By placement of the characteristiccurve along a position axis, the position of the magnet and thereforethe movable member may be determined.

In another conventional MR device, a position determining apparatus canbe implemented, which includes a magnet that is attached to a movablemember that moves along a predefined path of finite length. An array ofmagnetic field transducers can be located adjacent to the predefinedpath. The transducers can provide an output signal as the magnetapproaches passes and moves away from each transducer. A correctionmechanism can also be implemented to correct for residual error causedby the non-linearity of the transducers.

Such a correction mechanism preferably approximates the residual errorwith a predetermined function, and applies correction factors thatcorrespond to the predetermined function to offset the residual error.By correcting for the non-linearity of the transducers, the length ofthe magnet may be reduced and/or the spacing of the transducers may bereduced.

An example of a conventional magnetic sensing approach is disclosed, forexample, in U.S. Pat. No. 5,589,769, “Position Detection ApparatusIncluding a Circuit for Receiving a Plurality of Output Signal Valuesand Fitting the Output Signal Values to a Curve,” which issued to DonaldR. Krahn on Dec. 31, 1996, and is assigned to Honeywell InternationalInc. Another example of another conventional magnetic sensing approachis disclosed in U.S. Pat. No. 6,097,183, “Position Detection Apparatuswith Correction for Non-Linear Sensor Regions,” which issued to Goetz etal. on Aug. 1, 2000 and is also assigned to Honeywell International Inc.A further example of a conventional magnetic sensing system is disclosedin U.S. Pat. No. 6,806,702, “Magnetic Angular Position SensorApparatus,” which issued to Wayne A. Lamb et al on Oct. 19, 2004, andwhich is assigned to Honeywell International Inc. U.S. Pat. Nos.5,589,769, 6,097,183 and 6,806,702 are incorporated herein by reference.Such conventional MR-based devices generally utilize discrete componentson a Printed Circuit Board (PCB) assembly to yield the resultingfunction.

Because such conventional MR-based sensing devices, and in particularangle sensors, are required to be implemented in the context of smallpackage diameters, such devices are not feasible in situations wherethere is not enough room for a bias magnet to be positioned in a “fly bymode”. A magnetic circuit and sensor combination must therefore beimplemented, which occupies less space.

Some systems utilize AMR bridges in association with simple mathematicalfunctions such as ATAN (Inverse Tangent function) to determine absoluteposition data. One of the problems with utilizing mathematical functionssuch as ATAN is the in order to achieve high accuracy with this method,the AMR bridge signals must be as close to perfect sinusoids (i.e., Sin2X and Cos 2X) as possible. To date, such goals have not beensufficiently achieved.

In order to overcome such problems, a new angular/rotary positionsensing scheme and algorithm thereof must be designed in order toachieve maximum performance benefits. It is believed that theembodiments disclosed herein address and satisfy these issues.

BRIEF SUMMARY

The following summary is provided to facilitate an understanding of someof the innovative features unique to the present invention and is notintended to be a full description. A full appreciation of the variousaspects of the embodiments can be gained by taking the entirespecification, claims, drawings, and abstract as a whole.

It is, therefore, one aspect of the present invention to provide for animproved magnetic sensing configuration based upon Hall-effect and/ormagnetoresistive components.

It is another aspect of the present invention to provide for an angularand rotary position sensor.

It is a further aspect of the present invention to provide for angularposition detection systems and methods utilizing a plurality of rotaryconfigured magnetic sensors.

The aforementioned aspects of the invention and other objectives andadvantages can now be achieved as described herein. Magnetic sensingmethods and systems are disclosed. In general, a die can be providedcomprising a central location thereof. A group of magnetoresistivebridge circuits are located and configured upon the die. A magneticbiasing component is then utilized to bias the plurality ofmagnetoresistive bridge circuits with a magnetic field rotating about anaxis of the central location of the die in order to generate a pluralityof bridge output signals thereof. Finally, the plurality of bridgeoutput signals are processed in order to determine position datathereof.

Thus, two or more magnetoresistive bridge circuits can share a centrallocation thereof. A magnetic biasing component can be positionedproximate to the two or more magnetoresistive bridge circuits, such thatthe magnetic biasing component is rotated about an axis thereof togenerate a magnetic field on the two or more magnetoresistive bridgecircuits, and wherein the magnetic field is approximately close to amagnetic vector rotating about the central location in order to provideangular and rotational data thereof.

The magnetic biasing component and the magnetoresistive bridgecomponents are separated from one another by a gap formed between themagnetic biasing component and the magnetoresistive bridge components.The magnetoresistive bridge circuits can generally include a pluralityof AMR and/or Hall effect components. The magnetoresistive bridgecircuits can be configured in the context of a four bridge 45° rotaryAMR array configuration, which is described in greater detail herein.Additionally, the magnetic biasing component can be rotated about theaxis thereof at a rotation angle that is selected from at least oneangle of an angular range between 0° and 1800.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, in which like reference numerals refer toidentical or functionally-similar elements throughout the separate viewsand which are incorporated in and form a part of the specification,further illustrate the embodiments and, together with the detaileddescription of the invention, serve to explain the principles of thepresent invention.

FIG. 1 illustrates a representative microelectronic package that wouldhouse a magnetic sensing component, which can be adapted for use inaccordance with one embodiment;

FIG. 2 illustrates rectangular and ring magnets, which can be adaptedfor use in accordance with one or more embodiments;

FIG. 3 illustrates a biasing system, which can be implemented inaccordance with an embodiment;

FIG. 4 depicts a schematic diagram of a two-magnetoresistive sensingbridge circuit, which can be implemented in accordance with one possibleembodiment.

FIG. 5 illustrates an alternative view of an AMR bridge circuit,including a representative field direction thereof that can beimplemented in accordance with an embodiment.

FIG. 6 illustrates an AMR sensing circuit with signal A and signal Bamplification thereof, in accordance with an embodiment;

FIG. 7 illustrates a graph of un-amplified output signals of AMR bridgecircuits for illustrative purposes;

FIG. 8 illustrates a graph of typical amplified output signals for AMRbridge circuits in accordance with an embodiment,

FIG. 9 illustrates a graph representing data generated as a result of asignal processing algorithm that can be implemented in accordance withan embodiment;

FIG. 10 illustrates a bias magnet configuration that can be implementedin accordance with an embodiment;

FIG. 11 illustrates a ring magnet configuration that can be implementedin accordance with an alternative embodiment;

FIG. 12 illustrates a layout of a die for a 4 bridge 45 degree rotaryAMR array system, in accordance with a preferred embodiment;

FIG. 13 illustrates a rotary AMR array system that can be implemented inaccordance with a preferred embodiment;

FIG. 14 illustrates a graph depicting output signals for a 4-bridge, 45degree rotary AMR array configuration that can be implemented inaccordance with one embodiment;

FIG. 15 illustrates a system of AMR bridge circuits arranged in ahalf-circular pattern in accordance with one embodiment;

FIG. 16 illustrates a system of AMR bridge circuits arranged in an ovalpattern in accordance with another embodiment;

FIG. 17 illustrates a system of AMR bridge circuits arranged in ahalf-circular pattern in accordance with one embodiment; and

FIG. 18 illustrates a system of AMR bridge circuits arranged in an ovalpattern in accordance with another embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The particular values and configurations discussed in these non-limitingexamples can be varied and are cited merely to illustrate one or moreembodiments and are not intended to limit the scope thereof.

FIG. 1 illustrates a representative microelectronic package that wouldhouse a magnetic sensing component 100, which can be adapted for use inaccordance with one embodiment. Magnetic sensing component 100 can beimplemented as an AMR bridge circuit and/or an amplifying ASIC device.Note that as utilized herein, the term “bridge circuit” and “bridge” canbe utilized interchangeably to refer to the same device or component.

When implemented as an AMR bridge circuit, magnetic sensing component100 can be configured to contain 2 co-located AMR bridge circuitsrotated 45 degrees from one another to provide sine and cosine signalsthereof. Magnetic sensing component 100 can be alternatively implementedto contain dual linear instrumentation amplifiers that provide signalconditioning for the aforementioned AMR bridge circuits or another typeof transducer, thereby providing sine and cosine signals thereof fromwhich data can be extracted for rotary and/or angular detection.

Magnetic sensing component 100 includes a plurality of electricalconnections thereof in the form of pins 112, 114, 116, 118, 120, 124,126 and 128. An integrated circuit is housed within sensing component100 and may contain the AMR sensing elements we well as any associatedamplifying components. Magnetic sensing component 100 can therefore beutilized for angular and/or rotary position sensing.

FIG. 2 illustrates respective rectangular and ring magnets 204 and 202,which can be adapted for use in accordance with one or more embodiments.The use of ring magnet 202 provides very low sensitivity to positionaltolerance magnets and AMR bridge circuits. Rectangular magnet 204, onthe other hand, when designed with physical dimensions providing for acost effective solution may yield higher sensitivity to positionaltolerances between magnet and AMR bridges. Ring magnet 202 can be formedfrom a material, such as, for example, compression molded NdFeB.Rectangular magnet 204 can be formed from a material, such as, forexample, sintered NdFeB. Although ring magnet 202 and rectangular magnet404 are discussed in accordance with some possible embodiments, it canbe appreciated that other dipole magnet designs can be optimized to meetpackaging requirements, depending upon the particular embodiment.

FIG. 3 illustrates a biasing system 300, which can be implemented inaccordance with an embodiment. Note that a side view 301 of system 300is depicted in FIG. 3, along with a top view 303 thereof. Note that inviews 301 and 303, identical or similar parts are generally indicated byidentical reference numerals. System 300 includes a shaft 310, which canbe formed from a ferrous or non-ferrous material. Shaft 310 is locatedadjacent to biasing magnet 308. A gap 309 is formed between magnet 308and magnetic sensing component 100, which was disclosed in greaterdetail in FIG. 1.

Magnet 308 can be implemented as, for example, rectangular and ringmagnets 204 and 202 respectively depicted in FIG. 2, or any combinationof magnets and pole pieces that would produce a uniform magnetic biasfield on magnetic sensing component 100. Magnetic sensing component canbe located on a printed circuit board (PCB) 302, which is connected to anon-ferrous base such as aluminum, thermoplastic, etc. 304. Note that inview 303, arrow 314 indicates a positive or negative 90° rotation ofshaft 310. System 300 therefore represents one possible biasingconfiguration.

FIG. 4 depicts a physical layout of two co-located AMR bridges on onedie, which can be implemented in accordance with one possibleembodiment. FIG. 4 generally illustrates a layout of eight resistorsarranged between two Wheatstone sensing bridges. It can be appreciatedby those skilled in the art that the configuration depicted in FIG. 4represents one of many possible magnetoresistive sensing designs thatcan be utilized in accordance with the invention described herein. Feweror additional resistors and/or resistor patterns can be utilized,depending on a desired application.

In FIG. 4, a first bridge circuit can include rectangular shapedresistor patterns 402, 414, 410, and 406 (i.e., respectively labeledresistors R1A, R2A, R3A, and R4A), which can be electrically connectedto form a single Wheatstone bridge. A second bridge circuit (i.e.,Bridge B), whose resistors are oriented at 45 degree to those of BridgeA and triangular in their shape patterns, is configured from resistors404, 416, 412, and 408 (i.e., respectively labeled resistors R1B, R2B,R3B, and R4B).

The four-axis symmetry of the eight-resistor layout pattern illustratedin FIG. 4 represents only one example of an arrangement of two sensingbridges. Other eight resistor patterns can be constructed, for example,having a less symmetrical or non-symmetrical arrangement but having alleight resistors with identical shape and size. At least two separatesensing bridges can thus share a common geometrical center point and canalso be rotated from one another (i.e., in this case 45° although otherangles are possible) to provide signals offset from one another.

Note that FIG. 5 illustrates an AMR bridge circuit 500, which isanalogous to the configuration depicted in FIG. 4. As indicated in FIG.5, a representative field direction 501 that rotates through AMR bridgesof circuit 500 when a magnet, such as magnet 308 rotates. AMR bridgecircuit 500 is generally formed from two AMR bridge circuits composed ofmagnetoresistors 502, 504, 506, 508, 510, 512, 514, and 516.

FIG. 6 illustrates a schematic diagram of an AMR sensing circuit 600with signal A and signal B amplification thereof, in accordance with anembodiment. Note that circuit 600 depicted in FIG. 6 schematicallyrepresents the electrical schematic of circuit 500 depicted in FIG. 5.Thus, two bridge circuits 602 and 604 are depicted in FIG. 6, which formcircuit 600. Bridge circuit 602 is therefore formed from a plurality ofmagnetoresistors 502, 506, 510, and 514, while bridge circuit 604 isformed from a plurality of magnetoresistors 504, 508, 512, and 516.Bridge circuit 602 is connected to an amplifier 603 in order to output asignal A, while bridge circuit 604 is connected to an amplifier 605 inorder to output a signal B.

FIG. 7 illustrates a graph 700 of un-amplified output signals of AMRbridge circuits, such as, AMR bridge circuits 602 and 604. Graph 700generally indicates data calculated as a result of a bridge outputversus rotation (in degrees). FIG. 8 illustrates a graph 800 of typicalamplified output signals for AMR bridge circuits (e.g., bridge circuits602, 604) in accordance with an embodiment. Notice that the signals fromthe AMR bridge repeat every 180 degrees, implying a SIN (2θ) function. A360 degree sensing capability can be easily achieved by adding a digitalHall switch to differentiate between north and south poles of the biasmagnet (e.g., magnet 308 of FIG. 3).

Note that a procedure can be implemented for processing sensor signalsutilizing a microprocessor. In general, a magnetic sensing system, suchas system 300 depicted in FIG. 3, can be calibrated at 25° C. byrotating the field and reading the sensor signals. During calibrationthe following are calculated:Offset A=(Max signal A+Min signal A)/2Offset B=(Max signal B+Min signal B)/2Amp A=(Max signal A−Min signal A)/2Amp B=(Max signal B−Min signal B)/2N=Amp A/Amp B

During actual operation the signals are fed into the A/D pins of themicroprocessor and the following formulas are used to determineposition:Signal A=Voltage A−Offset ASignal B=Voltage B−Offset BAngle=ATAN(Signal A/(Signal B*N))/2

The idea behind this approach is that all common mode effects fall outof the equation in a self compensating manner. For example, the bridgesignals A & B will vary the same amount over temperature. When thishappens the errors cancel out when Signal A and Signal B are divided.

FIG. 9 therefore illustrates an example of a graph 900 representing datagenerated as a result of implementing a signal processing algorithm asindicated above, in accordance with one embodiment. Note that the “ATAN”resultant value can indicated in the equations above can be plotted vialine 902 depicted in FIG. 9.

FIG. 10 illustrates a bias magnet 100 configuration that can beimplemented in accordance with one embodiment. In FIG. 10, two views areprovided. A top view 102 of bias magnet 100 along with a side view 104thereof. FIG. 11 illustrates a ring magnet 1100 configuration that canbe implemented in accordance with an alternative embodiment. Note thatin FIG. 11, four views of ring magnet 1100 are provided, including asectional view 1102, along with a top view 1104, a perspective top view1106 and a side view 1100. In general, ring magnet 1100 includes acentral opening 1101. In view 1104, the magnetization direction 1103 isdepicted. In general, view 1102 presents a sectional A-A view of ringmagnet 1100. Note that ring magnet 1100 depicted in FIG. 10 is generallyanalogous to ring magnet 202 depicted in FIG. 2.

FIG. 12 illustrates a layout of a die for a 4-bridge 45° rotary AMRarray system 1200, in accordance with a preferred embodiment. System1200 is generally composed of 4 bridge circuits formed fromMagnetoresistive elements electrically connected in a wheatstone bridgeconfiguration, components 1202, 1204, 1206 and 1208. System 1200 thuscan implement a rotary AMR sensing configuration in which the biasmagnet or magnetic bias circuit is rotated about an axis and themagnetic field generated on the AMR bridge or bridge circuit ispreferably as close to a magnetic vector rotating about the center,similar to the hands of a clock. Two or more AMR bridges can beimplemented in the configuration of system 1200.

FIG. 13 illustrates a rotary AMR array system 1300 that can beimplemented in accordance with a preferred embodiment. Note that inFIGS. 12-13, identical or similar parts or components are generallyindicated by identical reference numerals. Thus, system 1200 depicted inFIG. 12 can be utilized in association with system 1300. Rotation ofsystem 1200 is generally indicated by positions 1301, 1303, 1307 and1305. Initially, position 1301 indicates an angular position of −22.5degrees followed by position 1303, which indicates an angular positionof −7.5 degrees. Note that arrows 1302, 1304 and 1306 indicate theangular rotation of the resultant magnetic bias field or magnetic vectorat various rotational positions. Position 1307 indicates an angularposition of +7.5 degrees and position 1305 indicates an angular positionof +22.5 degrees. The magnetic vector is represented in FIG. 13 by arrowM. As the bias magnet or magnetic circuit rotates in angle, theresulting field on the die appears to be a uniform vector rotating aboutsimilar to the hand on a clock.

FIG. 14 illustrates a graph 1400 depicting differential bridge signalsfor a 4-bridge, 45 degree rotary AMR array configuration that can beimplemented in accordance with one embodiment. Graph 1400 thusrepresents one possible set of data that can be collected as a result ofthe angular movement illustrated in FIG. 13. Graph 1400 is thereforeassociated with system 1300. Note that although the aforementionedexamples describe a 4-bridge 45 degree sensor configuration, any numberof bridges greater than or equal to 2 can be implemented in accordancewith the embodiments. Additionally, any rotational angle between 0 and180 degrees can be utilized for such a rotary AMR array sensingconfiguration. Note that the reason 180 degrees is considered therotational angle limit for such a configuration is because permalloy(i.e., AMR) has a response proportional to SIN (2θ) and the outputrepeats every 180 degrees.

FIG. 15 illustrates a system 1500 of AMR bridge circuits 1502, 1504,1506, 1508, 1510, 1510, 1512, and 1514 arranged in a half-circularpattern in accordance with one embodiment. FIG. 16 illustrates a system1600 of AMR bridge circuits 1502, 1504, 1506, 1508, 1510, 1510, 1512,and 1514 arranged in an oval pattern in accordance with anotherembodiment.

FIG. 17 illustrates a system 1700 of AMR bridge circuits 1702, 1704,1706, 1708, 1710, 1712, and 1714 arranged in a half-circular pattern inaccordance with one embodiment. FIG. 18 illustrates a system 1800 of AMRbridge circuit 1702, 1704, 1706, 1708, 1710, 1712, and 1714 s arrangedin an oval pattern in accordance with another embodiment.

Based on the foregoing, it can be appreciated that the embodimentsdescribed herein generally teach a method and/or system in which a dieis provided with a central location thereof and a plurality ofmagnetoresistive bridge circuits are located and configured upon thedie. A magnetic biasing component is then utilized to bias themagnetoresistive bridge circuits (i.e., transducers) with a magneticfield rotating about an axis of the central location of the die in orderto generate a plurality of bridge output signals thereof. The bridgeoutput signals can then be processed in order to determine position datathereof.

Note that various magnetoresistive array algorithms and methods can beutilized to process the bridge output signals. Such MR array algorithmsand methods can be combined to process multiple signals with themulti-bridge transducer design biased with a magnetic field rotatingabout the axis of the center of the die, as indicated herein withoutlimiting the scope and breadth of the embodiments. One example of an MRarray algorithm and/or method that can be utilized to process the bridgeoutput signals is disclosed in U.S. Pat. No. 5,589,769, “PositionDetection Apparatus Including a Circuit for Receiving a Plurality ofOutput Signal Values and Fitting the Output Signal Values to a Curve,”which issued to Donald R. Krahn on Dec. 31, 1996, and is assigned toHoneywell International Inc.

U.S. Pat. No. 5,589,769 is incorporated herein by reference andgenerally describes an apparatus for determining the position of amember movable along a path. In U.S. Pat. No. 5,589,769, a magnet isattached to the movable member and an array of magnetic fieldtransducers are located adjacent the path. As the magnet approaches,passes and moves away from a transducer, the transducer provides avarying output signal which can be represented by a singlecharacteristic curve that is representative of any of the transducers.To determine the position of the movable member, the transducers areelectronically scanned and data is selected from a group of transducershaving an output that indicates relative proximity to the magnet. Acurve fitting algorithm is then used to determine a best fit of the datato the characteristic curve. By placement of the characteristic curvealong a position axis, the position of the magnet and therefore themovable member may be determined.

Another example of an MR array algorithm and/or method that can beutilized to process bridge output signals is disclosed in U.S. Pat. No.6,097,183, “Position Detection Apparatus with Correction for Non-LinearSensor Regions,” which issued to Goetz et al. on Aug. 1, 2000 and isalso assigned to Honeywell International Inc. U.S. Pat. No. 6,097,183 isincorporated herein by reference in its entirety and generally teaches aposition determining apparatus that does not require a relatively longmagnet and/or small sensor spacing. This is preferably achieved byproviding a correction mechanism to correct for residual error cause bythe non-linearity of the sensors. The correction mechanism preferablyapproximates the residual error with a predetermined function, andapplies selected correction factors that correspond to the predeterminedfunction to offset the residual error.

As indicated in U.S. Pat. No. 6,097,183, a magnet can be attached to amovable member, which moves along a predefined path of finite length. Anarray of magnetic field transducers can be located adjacent to thepredefined path. The transducers provide a bipolar output signal as themagnet approaches, passes and moves away from each transducer. Todetermine the position of the magnet, and thus the movable member, thetransducers can be electronically scanned and data selected from a groupof transducers having an output that indicates relative proximity to themagnet.

A ratio can then be calculated by dividing the amplitudes of the outputsignal values of the selected transducers in a predetermined way. Theposition of the magnet is then determined by applying a correctionfactor to the ratio. Preferably, the correction factor at leastpartially corrects for the non-linearity of the transducers.

To calculate the ratio, two adjacent transducers are preferably selectedwith the first transducer having a positive output signal value “A”, andthe second transducer having a negative output signal value “B” (thoughthese can be reversed). By using the output signal values A and B, aratio may be calculated that is related to the position of the magnetrelative to the first and second transducers, as described above.

An additional example of an MR array algorithm and/or method that can beutilized to process bridge output signals is disclosed in U.S. Pat. No.6,806,702, “Magnetic Angular Position Sensor Apparatus,” which issued toLamb et al on Oct. 19, 2004. and is also assigned to HoneywellInternational Inc. U.S. Pat. No. 6,806,702 is incorporated herein byreference in its entirety and generally teaches an angular positionsensing apparatus and method that involves the use of a rotatable baseand two or more magnets located proximate to one another upon therotatable base. The magnets are generally magnetized parallel andopposite to one another to create a uniform magnetic field thereof. Asensor is located external to the two magnets, such that the sensorcomes into contact with the uniform magnetic field to sense a change inangular position associated with the rotatable base.

The sensor can be mounted on a printed circuit board (PCB), which isalso located external to the magnets. Such a sensor can be configuredas, for example, a Hall sensor or a magnetoresistive sensor. If thesensor is configured as a magnetoresistive sensor, such amagnetoresistive sensor can also include a plurality of magnetoresistorsarranged within a magnetoresistive bridge circuit. Alternatively, themagnetoresistive sensor can include two magnetoresistive bridge circuitsintegrated with one another in a Wheatstone bridge configuration,wherein each of the magnetoresistive bridge circuits comprises fourmagnetoresistors. The sensor described herein can be configured, forexample, as an integrated circuit.

Note that the aforementioned methodologies generally disclose techniquesfor processing bridge output signals in order to determine position datathereof. Such techniques can be implemented in the context of a moduleor a group of modules, depending upon design considerations. In thecomputer programming arts, a “module” can be typically implemented as acollection of routines and data structures that performs particulartasks or implements a particular abstract data type. Modules generallyare composed of two parts. First, a software module may list theconstants, data types, variable, routines and the like that that can beaccessed by other modules or routines. Second, a software module can beconfigured as an implementation, which can be private (i.e., accessibleperhaps only to the module), and that contains the source code thatactually implements the routines or subroutines upon which the module isbased. Thus, for example, the term module, as utilized herein generallyrefers to software modules or implementations thereof. Such modules canbe utilized separately or together to form a program product that can beimplemented through signal-bearing media, including transmission mediaand recordable media.

Thus, for example, a processing module for processing a plurality ofbridge output signals in order to determine position data thereof can beprovided in association with a die comprising a central locationthereof, wherein a plurality of magnetoresistive bridge circuits arelocated and/or configured upon the die. Such a module can also beprovided in association with a magnetic biasing component for biasingthe plurality of magnetoresistive bridge circuits with a magnetic fieldrotating about an axis of the central location of the die in order togenerate a plurality of bridge output signals thereof, wherein theplurality of magnetoresistive bridge circuits are biased utilizing amagnetic biasing component. Such components, together with theprocessing module can be said to form a “system”.

Such a processing module can determine position data by calculating aratio of the plurality of bridge output signals of selectedmagnetoresistive bridge circuits among the plurality of magnetoresistivebridge circuits applying a selected correction factor to the ratio todetermine the position data. The selected correction factor can beselected from a number of correction factors. The number of correctionfactors may collectively fall along a predetermined function comprising,for example, a sinusoidal function. Alternatively, the processing modulemay fit the plurality of bridge output signals to one or more curves andutilize a crossover point of the curve(s) to determine the positiondata.

Such a processing module can also be configured to determine acharacteristic curve for at least one magnetoresistive bridge circuitamong the plurality of magnetoresistive bridge circuits as the magneticbiasing component approaches, passes and moves away from themagnetoresistive bridge circuit(s), and thereafter fit the plurality ofbridge output signals to the characteristic curve to determine theposition data.

It will be appreciated that variations of the above-disclosed and otherfeatures and functions, or alternatives thereof, may be desirablycombined into many other different systems or applications. Also thatvarious presently unforeseen or unanticipated alternatives,modifications, variations or improvements therein may be subsequentlymade by those skilled in the art which are also intended to beencompassed by the following claims.

1. A magnetic sensing method, comprising: providing a die comprising acentral location thereof; locating a plurality of magnetoresistivebridge circuits upon said die, said plurality of magnetoresistive bridgecircuits comprises a rotary AMR array configuration; biasing saidplurality of magnetoresistive bridge circuits with a magnetic fieldrotating about an axis of said central location of said die in order togenerate a plurality of bridge output signals thereof, wherein saidplurality of magnetoresistive bridge circuits are biased utilizing amagnetic biasing component; and processing said plurality of bridgeoutput signals in order to determine position data thereof.
 2. Themethod of claim 1 wherein processing said plurality of bridge outputsignals in order to determine position data thereof, further comprises:determining said position data by calculating a ratio of said pluralityof bridge output signals of selected magnetoresistive bridge circuitsamong said plurality of magnetoresistive bridge circuits; and applying aselected correction factor to the ratio to determine said position data.3. The method of claim 2 further comprising selecting said selectedcorrection factor from a number of correction factors.
 4. The method ofclaim 3 wherein said number of correction factors collectively fallalong a predetermined function.
 5. The method of claim 4 wherein saidpredetermined function comprises a sinusoidal function.
 6. The method ofclaim 1 wherein processing said plurality of bridge output signals inorder to determine position data thereof, further comprises: fittingsaid plurality of bridge output signals to at least one curve; and usinga crossover point of said at least one curve to determine said positiondata.
 7. The method of claim 1 wherein processing said plurality ofbridge output signals in order to determine position data thereof,further comprises: determining a characteristic curve for at least onemagnetoresistive bridge circuit among said plurality of magnetoresistivebridge circuits as said magnetic biasing component approaches, passesand moves away from said at least one magnetoresistive bridge circuit;and fitting said plurality of bridge output signals to saidcharacteristic curve to determine said position data.
 8. A magneticsensing method of claim 1, comprising: providing a die comprising acentral location thereof; locating a plurality of magnetoresistivebridge circuits upon said die, wherein said plurality ofmagnetoresistive bridge circuits comprises a four bridge 45° rotary AMRarray configurations; biasing said plurality of magnetoresistive bridgecircuits with a magnetic field rotating about an axis of said centrallocation of said die in order to generate a plurality of bridge outputsignals thereof, wherein said plurality of magnetoresistive bridgecircuits are biased utilizing a magnetic biasing component; andprocessing said plurality of bridge output signals in order to determineposition data thereof.
 9. The method of claim 8 wherein said magneticbiasing component is rotated about said axis at a rotation angle that isselected from at least one angle of an angular range between 0° and180°, wherein said magnetic biasing component biases said plurality ofmagnetoresistive bridge circuits with said magnetic field rotating aboutsaid axis of said central location of said die in order to generate saidplurality of bridge output signals thereof.
 10. The method of claim 8wherein each of said plurality of magnetoresistive bridge circuitscomprises at least one transducer.
 11. (canceled)
 12. A magnetic sensingsystem, comprising: a die comprising a central location thereof; aplurality of magnetoresistive bridge circuits located upon said die,wherein said plurality of magnetoresistive bridge circuits comprises afour bridge 45° rotary AMR array configuration; a magnetic biasingcomponent for biasing said plurality of magnetoresistive bridge circuitswith a magnetic field rotating about an axis of said central location ofsaid die in order to generate a plurality of bridge output signalsthereof; and a module for processing said plurality of bridge outputsignals in order to determine position data thereof.
 13. The system ofclaim 12 wherein said module: determines said position data bycalculating a ratio of said plurality of bridge output signals ofselected magnetoresistive bridge circuits among said plurality ofmagnetoresistive bridge circuits; and applies a selected correctionfactor to the ratio to determine said position data.
 14. The system ofclaim 13 further comprising selecting said selected correction factorfrom a number of correction factors.
 15. The system of claim 14 whereinsaid number of correction factors collectively fall along apredetermined function.
 16. The system of claim 15 wherein saidpredetermined function comprises a sinusoidal function.
 17. The systemof claim 12 wherein said module: fits said plurality of bridge outputsignals to at least one curve; and utilizes a crossover point of said atleast one curve to determine said position data.
 18. The system of claim12 wherein said module: determines a characteristic curve for at leastone magnetoresistive bridge circuit among said plurality ofmagnetoresistive bridge circuits as said magnetic biasing componentapproaches, passes and moves away from said at least onemagnetoresistive bridge circuit; and fits said plurality of bridgeoutput signals to said characteristic curve to determine said positiondata.
 19. (canceled)
 20. The system of claim 12 wherein said magneticbiasing component is rotated about said axis at a rotation angle that isselected from at least one angle of an angular range between 0° and180°, wherein said magnetic biasing component biases said plurality ofmagnetoresistive bridge circuits with said magnetic field rotating aboutsaid axis of said central location of said die in order to generate saidplurality of bridge output signals thereof.
 21. The system of claim 12wherein each of said plurality of magnetoresistive bridge circuitscomprises at least one transducer.